If left unprotected, integrated circuits (ICs) are subject to alteration, by either deletion of design data or insertion of such data. Such alteration may be particularly unwanted when the IC is used in sensitive applications. Conventionally, a determination of whether an IC has been altered by deletion of design data can be done using built-in self-testing (BIST). However, detecting the addition of malicious circuitry poses a more challenging problem. Further, even when checking for deletions using BIST, each device in the IC must be checked. Thus, conventional methods, such as BIST, are not optimally effective in securing ICs against alteration.